You will need to post some data then, which reproduces the problem, as your code does not show anything that I recognize as triggering such behaviour. Please make sure before posting that no sensitive data gets posted and that the posted data actually produces the behaviour you describe. Although I'm no user of Emacs, the ^@ character could be its interpretation of "\0". Which still is weird, but without seeing your input data, it's hard to tell where it comes from. Also, your Perl version (perl -v) might be of interest.